A prototype instrument has been constructed and improved which allows the monitoring of blood cultures with an electrical impedance detector. This has been connected to a laboratory computer, which can then be queried about the status of cultures. BIBLIOGRAPHIC REFERENCES: Zierdt, C.H., Kagan, R.L. and MacLowry, J.D.: Development of Lysis-Filtration Blood Culture Technique. J. Clin. Microbiol. 5:46-50, 1977. Kagan, R.L., Schuette, W.H., Zierdt, C.H. and MacLowry, J.D.: Rapid Automated Diagnosis of Bacteremia by Impedance Detection. J. Clin. Microbiol. 5:51-57, 1977.